European 0,160,278 describes and illustrates such a cutting inserts This cutting insert has below the cutting edge and spaced therefrom a side-face region reaching to the support face that is set back relative to the overlying side-surface region that goes to the cutting edge.
In addition cutting inserts, in particular rhombic cutting inserts with acute-angle corners, are known which have on the side face at a spacing from the cutting edge below the corner region a set-back side face produced by machining. The transition regions between two adjacent side-face sections run together at an ever acuter angle toward the support face or have seen in section a constant corner radius of the transition regions between two side faces.
The disadvantage of the above-described cutting inserts is that they either have very small corner radiuses below a cutting-insert support face at a cutting corner, so that there is the danger of breakage, -or with set-back side-face transition regions the support face is made very small which reduces the stability of an indexable cutting place installed in a tool holder. As the side-face regions are worn off increased costs and labor are encountered Corner regions with small radiuses in the region of the support face are very hard to manufacture by pressing.